Digital Charts/ChartKits & FreeBoatingCharts.com: General: FreeBoatingCharts.com - Use of downloads, etc.: free boating charts and new iGPS USB GPS receiver
You will need charting software to interface with the GPS and view charts, such as, our Offshore Navigator. See this link for details on available products: http://www.maptech.com/water/index.cfm
The GPS also comes with a disk containing drivers to allow the GPS to communicate with the computer.